The proposed studies represent a continuation and expansion of current efforts investigating growth hormone (GH) and prolactin (PRL) synthesis, storage, and release in normal, non-euthyroid, and fetal pituitary, as well as in tumor tissue. Through clarification of the range and mechanisms of available somatotroph/lactotroph responses, these efforts seek to refine and exploit an assay by which the mechanism of action of various secretagogues can be identified and pharmacologically manipulated. The secretion of both GH and PRL appear to result from the tonic interplay of both releasing and inhibiting hypothalamic factors even one of which may have multiple effects upon individual cells. Hormone release may occur from physiologically separable intracellular storage pools, and the released hormone may exhibit molecular size heterogeneity and variable bio-potency. Thus multiple subcellular sites may be available for pharmacologic manipulation, and measurement of net hormone release or pituitary content may be inadequate to study control mechanisms responsible for hormone release, storage, and synthesis. This proposal continues to use an in vitro perifusion system of rat adenophypophyses or tumor cells, with or without rat hypothalami, exposed to (3H)- or (14C)- tagged amino acids. Manipulations prior to sacrifice focus in vitro studies upon specific aspects of the synthesis/storage/secretion mechanisms. Thus, rats may be of altered thyroid or nutritional status, and/or pretreated with hormone-specific antisera. In an attempt to remove neural influences, rat pituitaries will be transplanted to the kidney capsule, or remain in situ after electrolytic destruction of the ventral and/or dorsal medial hypothalamic nucleus. Hormone assay will be by specific immuno-precipitation and radioimmunoassay. Electron microscopy will attempt to make morphologic identification of subcellular events. Direct or hypothalamus-mediated cell response to secretagogues with or without in vitro disruptions of subcellular mechanisms will continue to be investigated. The applicant hopes to distinguish between factors with similar effects but different actions, to begin to eluicidate functional differences between normal and tumorous hormone producing cells and to detect in biological materials the simultaneous presence of factors with simultaneous presence of factors with opposing effects.